The proposed investigation has two major objectives. The first objective is to develop sensitive, clinically useful techniques to quantitate levels of Melphalan and its metabolites in blood and urine in order to determine the pharmacokinetics of this antineoplastic drug. The clinical applicability of these drug monitoring techniques can be readily assessed using biologic fluids obtained ancillary to those regularly obtained from patient population receiving Melphalan therapy at this Medical Center. The second objective is to probe more deeply into the antineoplastic mechanism of Melphalan by characterizing its distribution in tissues and the sites of its covalent binding to cellular nucleic acids, proteins and lipids. Use of radio-labeled 14(C-ring) Melphalan will facilitate these metabolic studies. A comparative study will be done of its dechlorinated dihydroxylated metabolites which should become incorporated into tissue macromolecules by normal synthetic pathways as differentiated from Melphalan incorporation by alkylation.